Minecraft: Zombies aren't being attracted to Villagers

I've made a Zombie XP Farm which has been working pretty well by using the new water elevator which uses the soul sand to push them up. In order for the elevator to work though, I have to surround the water sources with solid blocks.

Previously, in my old model the zombies had to push each other into the water elevator through two fence gates which worked but it was a slow process as they often wanted to go against the current that was pushing them into the elevator. So, I figured why don't I use myself as bait to cause them to want to get into the elevator by placing myself on the opposite side of the water elevator using signs to prevent the water from spilling on my side which worked really well.

After that, I thought to myself, "Why don't I just place a Villager in my place to attract the zombies into the water elevator so that I won't have to keep going down there to attract them". After placing in the Villager, I noticed that the zombies had no interest in attacking him. They kept wanting to go against the current, they weren't even looking at the Villager, and the process was as slow as the old model without bait.

Does anyone know what the problem could be? I thought that Zombies in the Java Edition of Minecraft could see through ALMOST anything including glass, ladders, slabs, fence gates, and signs at a far distance. I tried all of these to see if they would be able to see the Villager but it doesn't seem to work. They only seem to be attracted to me when I put myself as bait.

Please let me know if there's anything that I need to clarify or elaborate on. Thanks!

Solution 1:

As far as I can tell from the image, the villager's head is on the same level as the water stream, which I assume is the level of the zombies' legs. Therefore the zombie's line of sight is one block above the villager, causing it to ignore him, so try raising the villager by one block and see if it works, or remove the block above the end water stream so that if the zombies look down they can see the villager clearly.

Sorry if I got this wrong, I cannot comment.